scholarly journals THE ROLE OF SHEAR IN DISSIPATIVE GRAVITATIONAL COLLAPSE

2014 ◽  
Vol 23 (02) ◽  
pp. 1450013 ◽  
Author(s):  
M. GOVENDER ◽  
K. P. REDDY ◽  
S. D. MAHARAJ
Keyword(s):  
Hydrostatic Equilibrium ◽  
The Core ◽  
Radial Heat ◽  
Free Case ◽  
Radiating Star ◽  
Heat Transport Equation ◽  
Physical Features ◽  
Radial Heat Flux ◽  
Collapse Process

In this paper, we investigate the physics of a radiating star undergoing dissipative collapse in the form of a radial heat flux. Our treatment clearly demonstrates how the presence of shear affects the collapse process; we are in a position to contrast the physical features of the collapsing sphere in the presence of shear with the shear-free case. By employing a causal heat transport equation of the Maxwell–Cattaneo form we show that the shear leads to an enhancement of the core temperature thus emphasizing that relaxational effects cannot be ignored when the star leaves hydrostatic equilibrium.

The influence of an equation-of-state during radiative collapse

2016 ◽  
Vol 26 (07) ◽  
pp. 1750065 ◽  
Author(s):  
M. Govender ◽  
R. S. Bogadi ◽  
S. D. Maharaj
Keyword(s):  
Heat Flux ◽  
Equation Of State ◽  
State Parameter ◽  
Hydrostatic Equilibrium ◽  
Temperature Profiles ◽  
Equation Of State Parameter ◽  
Radial Heat ◽  
Radiating Star ◽  
Radial Heat Flux ◽  
Radiative Collapse

We study the role played by an equation-of-state during gravitational collapse of a radiating star. Starting from an initially static matter configuration obeying a linear equation-of-state, the star loses hydrostatic equilibrium and undergoes dissipative collapse in the form of a radial heat flux. We show that the equation-of-state parameter plays an important role in determining the temperature profiles of the collapsing body.

Dissipative collapse of a Karmarkar star

2020 ◽  
Vol 35 (20) ◽  
pp. 2050164 ◽  
Author(s):  
M. Govender ◽  
A. Maharaj ◽  
Ksh. Newton Singh ◽  
Neeraj Pant
Keyword(s):  
Stellar Structure ◽  
Spherically Symmetric ◽  
Isotropic Coordinates ◽  
Radial Heat ◽  
Radiating Star ◽  
Physical Tests ◽  
Dynamical Nature ◽  
Radial Heat Flux ◽  
Radiative Collapse ◽  
Static Core

In this paper, we employ the Karmarkar condition to model a spherically symmetric radiating star undergoing dissipative gravitational collapse within the framework of classical general relativity. The collapse ensues from an initial static core satisfying the Karmarkar condition in isotropic coordinates and proceeds nonadiabatically by emitting energy in the form of a radial heat flux to the exterior Vaidya spacetime. We show that the dynamical nature of the collapse is sensitive to the initial static configuration that inherently links the embedding to the final remnant. Our model considered several physical tests on how an initially static stellar structure onset to a radiative collapse.

scholarly journals A perturbative approach to the time-dependent Karmarkar condition

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
Megandhren Govender ◽  
Wesley Govender ◽  
Kevin P Reddy ◽  
Sunil D Maharaj
Keyword(s):  
Boundary Condition ◽  
Heat Flux ◽  
Gravitational Collapse ◽  
Time Dependent ◽  
Perturbative Approach ◽  
Radial Heat ◽  
Radiating Star ◽  
Static Regime ◽  
Radial Heat Flux ◽  
Static Core

AbstractIn this work we employ a perturbative approach to study the gravitational collapse of a shear-free radiating star. The collapse proceeds from an initial static core satisfying the time-independent Karmarkar condition and degenerates into a quasi-static regime with the generation of energy in the form of a radial heat flux. The time-dependent Karmarkar condition is solved together with the boundary condition to yield the full gravitational behaviour of the star. Our model is subjected to rigorous regularity, causality and stability tests.

scholarly journals NONADIABATIC SPHERICAL COLLAPSE WITH A TWO-FLUID ATMOSPHERE

2013 ◽  
Vol 22 (07) ◽  
pp. 1350049 ◽  
Author(s):  
M. GOVENDER
Keyword(s):  
Heat Flux ◽  
Heat Transport ◽  
Line Element ◽  
Spherically Symmetric ◽  
Spherical Collapse ◽  
Radial Heat ◽  
Heat Transport Equation ◽  
Symmetric Star ◽  
Radial Heat Flux ◽  
Two Fluid

In this paper, we present an exact model of a spherically symmetric star undergoing dissipative collapse in the form of a radial heat flux. The interior of the star is matched smoothly to the generalized Vaidya line element representing a two-fluid atmosphere comprising null radiation and a string fluid. The influence of the string density on the thermal behavior of the model is investigated by employing a causal heat transport equation of Maxwell–Cattaneo form.

THE SOIL PATTERN AND TRENDS IN WEST COAST AGRICULTURE SINCE 1964

1981 ◽  
pp. 19-28 ◽  
Author(s):  
D.B. Wright
Keyword(s):  
West Coast ◽  
Land Development ◽  
Dairy Production ◽  
Waste Land ◽  
Development Costs ◽  
Coastal Soils ◽  
Physical Features ◽  
Soil Pattern ◽  
Great Scope

The physical features, climate and soils of the West Coast are described. Expansion since 1964 of dairy production, sheep and beef cattle numbers, and areas of improved grassland are highlighted, as is the role of the Crown in land development and settlement. While isolation and distance, development costs, river problems, and farmer attitude and knowledge are considered limitations, great scope exists for increased production by the adoption, of more intensive techniques, including horticulture on the best coastal soils, and by development of waste land.

Does a Ribosome Really Read? On the Cognitive Roots and Heuristic Value of Linguistic Metaphors in Molecular Genetics. Part 2

2020 ◽  
Vol 63 (2) ◽  
pp. 46-62
Author(s):  
Suren T. Zolyan
Keyword(s):  
Information Processing ◽  
Genetic Information ◽  
Formal Organization ◽  
Dual Nature ◽  
Reading Frame ◽  
The Core ◽  
Genetic Information Processing ◽  
Cognitive Frame ◽  
Effective Instrument

We discuss the role of linguistic metaphors as a cognitive frame for the understanding of genetic information processing. The essential similarity between language and genetic information processing has been recognized since the very beginning, and many prominent scholars have noted the possibility of considering genes and genomes as texts or languages. Most of the core terms in molecular biology are based on linguistic metaphors. The processing of genetic information is understood as some operations on text – writing, reading and editing and their specification (encoding/decoding, proofreading, transcription, translation, reading frame). The concept of gene reading can be traced from the archaic idea of the equation of Life and Nature with the Book. Thus, the genetics itself can be metaphorically represented as some operations on text (deciphering, understanding, code-breaking, transcribing, editing, etc.), which are performed by scientists. At the same time linguistic metaphors portrayed gene entities also as having the ability of reading. In the case of such “bio-reading” some essential features similar to the processes of human reading can be revealed: this is an ability to identify the biochemical sequences based on their function in an abstract system and distinguish between type and its contextual tokens of the same type. Metaphors seem to be an effective instrument for representation, as they make possible a two-dimensional description: biochemical by its experimental empirical results and textual based on the cognitive models of comprehension. In addition to their heuristic value, linguistic metaphors are based on the essential characteristics of genetic information derived from its dual nature: biochemical by its substance, textual (or quasi-textual) by its formal organization. It can be concluded that linguistic metaphors denoting biochemical objects and processes seem to be a method of description and explanation of these heterogeneous properties.

Exploring the Mechanism of Lingzhu San in Treating Febrile Seizures by Using Network Pharmacology

2020 ◽  
Vol 23 ◽  
Author(s):  
Xiao Zhou ◽  
Xiao-Fei Zhang ◽  
Dong-Yan Guo ◽  
Yan-Jun Yang ◽  
Lin Liu ◽  
...  
Keyword(s):  
Febrile Seizures ◽  
Network Pharmacology ◽  
Biological Processes ◽  
Active Compounds ◽  
Potential Core ◽  
R Language ◽  
The Core ◽  
Multiple Factors ◽  
Therapeutic Mechanism

Objective: Lingzhu San (LZS) is a traditional Chinese medicine (TCM) prescription which can be effective in treating febrile seizures (FS) and has few researches on the mechanisms. In order to better guide the clinical use of LZS, we used the research ideas and methods of network pharmacology to find the potential core compounds, targets and pathways of LZS in the complex TCM system for the treatment of FS, and predict the mechanism. Materials and Methods: Databases such as BATMAN, TCMSP, TCMID, and SWISS TARGET are used to mine the active compounds and targets of LZS, and the target information of FS was obtained through GENECARDS and OMIM. Using Venny2.1.0 and Cytoscape software to locked the potential core compounds and targets of FS. The R language and ClusterProfiler software package were adopt to enrich and analyze the KEGG and GO pathways of the core targets and the biological processes and potential mechanisms of the core targets were revealed. Results: 187 active compounds and 2113 target proteins of LZS were collected. And 38 potential core compounds, 35 core targets and 775 metabolic and functional pathways were screened which involved in mediating FS. Finally, the role of the core compounds, targets and pivotal pathways of LZS regulated FS in the pathogenesis and therapeutic mechanism of FS was discussed and clarified. Conclusions: In this paper, the multi-compounds, multi-targets and multi-pathways mechanism of LZS in the treatment of FS was preliminarily revealed through the analysis of network pharmacology data, which is consistent with the principle of multi-compounds compatibility of TCM prescriptions and unified treatment of diseases from multiple angles, and it provides a new way for TCM to treat complex diseases caused by multiple factors.

Acid ceramidase, a double-edged sword in cancer aggression: A minireview

2020 ◽  
Vol 20 ◽  
Author(s):  
Helen Shiphrah Vethakanraj ◽  
Niveditha Chandrasekaran ◽  
Ashok Kumar Sekar
Keyword(s):  
Cell Fate ◽  
Cancer Progression ◽  
Potential Role ◽  
Tumour Progression ◽  
Acid Ceramidase ◽  
The Core ◽  
The Past ◽  
Sphingosine 1 Phosphate ◽  
Key Enzyme

: Acid ceramidase (AC), the key enzyme of the ceramide metabolic pathway hydrolyzes pro-apoptotic ceramide to sphingosine, which by the action of sphingosine-1-kinase is metabolized to mitogenic sphingosine-1-phosphate. The intracellular level of AC determines ceramide/sphingosine-1-phosphate rheostat which in turn decides the cell fate. The upregulated AC expression during cancerous condition acts as a “double-edged sword” by converting pro-apoptotic ceramide to anti-apoptotic sphingosine-1-phosphate, wherein on one end, the level of ceramide is decreased and on the other end, the level of sphingosine-1-phosphate is increased, thus altogether aggravating the cancer progression. In addition, cancer cells with upregulated AC expression exhibited increased cell proliferation, metastasis, chemoresistance, radioresistance and numerous strategies were developed in the past to effectively target the enzyme. Gene silencing and pharmacological inhibition of AC sensitized the resistant cells to chemo/radiotherapy thereby promoting cell death. The core objective of this review is to explore AC mediated tumour progression and the potential role of AC inhibitors in various cancer cell lines/models.

The Fox Diet

2018 ◽  
Author(s):  
Yochai Benkler ◽  
Robert Faris ◽  
Hal Roberts
Keyword(s):  
First Year ◽  
Right Wing ◽  
Justice Department ◽  
Fox News ◽  
The Core ◽  
Deep State ◽  
Media Ecosystem ◽  
Conservative Media ◽  
The Right

This chapter focuses on the role of the dominant player in conservative media, Fox News, during the first year of Donald Trump’s presidency. It looks at three case studies to illustrate how Fox News used its position at the core of the right-wing media ecosystem repeatedly to mount propaganda attacks in support of Trump: the Michael Flynn firing in March 2017, when Fox adopted the “deep state” framing of the entire controversy; the James Comey firing and Robert Mueller appointment in May 2017; when Fox propagated the Seth Rich murder conspiracy; and in October and November, when the arrests of Paul Manafort and guilty plea of Flynn seemed to mark a new level of threat to the president, Fox reframed the Uranium One story as an attack on the integrity of the FBI and Justice Department officials in charge of the investigation.

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